Dies employed in the drawing of metals and particularly those employed in the wire drawing art are usually formed by encasing a carbide insert in a steel casing. The insert is usually provided with a conical or tapered area which forms the front of the die and normally extends from about two-thirds to three-quarters through the insert and terminates in an orifice or opening commonly referred to as the land portion at the rear end of the die which defines the size or diameter of the object formed when the metal stock, usually in the form of a rod, is drawn through the die.
In the wire drawing art, the size of the orifice or land portion at the rear end of the die will determine the size or diameter of the wire by drawing the metal stock through the land or die opening. As can be appreciated, and notwithstanding the fact that the die insert is usually made of an extremely hard substance such as carbides, the die orifice or land portion as well as the walls of the conical or tapered portion of the die are subjected to wear due to the passage of metal therethrough and when this occurs the wire emanating from the die orifice or opening will have imperfections on the outer surface thereof such as scratch marks or the like. To avoid the formation of such imperfections on the drawn wire, the used die is removed from it's mounting on a drawing frame structure and the same is then subjected to a reconditioning operation. When a die is to be reconditioned, the die is usually mounted on a rotating head-stock of a lathe-type apparatus and a reconditioning tool having the required external dimensions is mounted on a spindle which is caused to simultaneously reciprocate and counter rotate with respect to the aforesaid head-stock and to engage with the said conical walls and the die opening or land portion to recondition the same.
The lapping tool for polishing the conical portion of the die comprises a metal pin-like member having a tapered portion at one end thereof which is designed to engage in point contact only the conical tapered wall of the die. A lapping tool for reconditioning the land portion of the die in a polishing operation, comprises a metal pin-like member having an external diameter slightly lesser than the diameter of the land to be reconditioned, and here again the tool engages the land portion in point contact only. The lapping tool for rough grinding a die comprises a metal pin-like member having a tapered portion at one end thereof and during the lapping operation the tapered portion of the tool engages the entire area of the tapered portion of the die to thereby remove by ripping from therein the burrs or other imperfections formed therein by reason of the metal being drawn therethrough. Also, in rough grinding a die, the land portion thereof can likewise be reconditioned by employing a tool having a slightly larger diameter than the diameter of the land portion to be reconditioned and to cause said tool to cut away some of the land area thus enlarging the land area so that when the die is again used in a wire drawing operation, the wire issuing from the die will be larger in diameter than the wire drawn from the die prior to the same having been reconditioned, as aforesaid. As can be appreciated, if the land portion is not subjected to a reconditioning operation, but only the tapered portion reconditioned, the size of the wire emanating from the die will remain the same as that drawn previously from the same die.
While in most metal drawing operations it is desirable to employ a die which has been subjected to a polishing operation to insure the removal of all imperfections from the tapered wall as well as the land portion of the die, to thereby produce a wire free of any imperfections on the outer surface thereof, there are instances where a die which has been subjected only to a rough grinding operation will be found satisfactory to form a wire which will be acceptable notwithstanding the slight imperfections appearing on the outer surface thereof.
Normally, the carbide insert in a die having a steel casing extending along the outer periphery thereof, will permit for the die to be repeatedly reconditioned to thus prolong the life of the die although, as stated above, following each such reconditioning operation, if the land portion of the die has been enlarged due to such reconditioning operation, the die will then be employed to draw a wire therethrough of a larger diameter.
In a lapping operation the lapping tool is mounted on a spindle which is caused to counter rotate with respect to the rotation of a head-stock on which has been mounted a die to be reconditioned, and to simultaneously reciprocate the spindle so as to engage the surfaces of the conical area of the die opening or land portion thereof, so that these surfaces are subjected to a ripping or polishing action to recondition these surfaces.
With the above in mind, it is the primary object of the invention to provide a means whereby the length of reciprocating travel of the rotation spindle having the lapping tool mounted thereon may be regulated.
Another object of the invention is to mount a rotating hub on the main drive shaft of a lathe-type machine tool and to provide a slot therein in which will be adjustably positioned and secured therein a plate member which will determine the length of the to and fro movement of the rotating spindle having the lapping tool mounted thereon.
Another object of the invention is to provide an apparatus which will enable a die to be perfectly centered in a chuck extending from a headstock whereby once the die has been centered in the chuck, the rough grinding of the die, including not only the tapered portion of the die but the land portion as well may be reconditioned should it be necessary to recondition this area of the die, the only change necessary to effect the reconditioning of the tapered wall of the die and the land portion, is a change in the lapping tool which is employed in these reconditioning operations.
Another object of the invention is to provide an adjustable linkage between the rotating and reciprocating spindle whereupon when the plate arrangement on the rotating hub structure is shifted from one position to another, the linkage can likewise be adjusted to vary the length of the linkage between these parts of the apparatus.
Another object of the invention is to provide a plurality of marker indications on the plate extending in the slot formed in the rotating hub to thus enable one to readily vary and determine the length of reciprocating travel of the spindle and lapping tool mounted thereon.
Another object of the invention is to provide a die reconditioning apparatus which is fully automatic in operation and which is relatively free of moving parts thus rendering the same to be substantially trouble free.
Further objects and advantages of the invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.